Demulsifiable lubricant compositions



United States Patent Ofiice 3,073,781 Patented Jan. 15, 1963 This invention relates to improvements in lubricant compositions. More particularly this invention relates to petroleum oil compositions having improved demulsibility characteristics and to the method of preparing such compositions.

In many applications of petroleum compositions, particularly lubricants such as gear lubricants, automotive engine lubricants, etc., the oil becomes mixed with water, and relatively'stable oil-in-water emulsionsare formed. In order to reuse the oil the contaminating water must be removed. If the oil does not readily demulsify or separate from the water, the use of such products as lubricants is materially decreased.

An object of this invention is a hydrocarbon oil composition having improved demulsifiable characteristics. Another object of the invention is a compounded lubricant composition which will readily separate from water when contaminated with or emulsified with water. A further object of the invention is a lubricant composition which is resistant to the formation of emulsions when used in the presence of water or when contaminated with water. A still further object of the invention is a method of imparting demulsibility characteristics to lubricant compositions. Other objects and advantages of the present invention will become apparent from the following description thereof,

.The present invention provides lubricant compositions having improved demulsibility characteristics comprising a major amount of a base oil, from about 0.1 to pref erably from about 0.5 to 2%, of a zinc dialkyl dithiophosphate having the general formula:

SOR

in which the Rs represent the same or diflferent alkyl groups which may contain from about 3 to 16 carbon atoms, and from 1 to based upon the total amount of the zinc dialkyl dithiophosphate added to the base oil, of an alkali metal salt of sulfonated castor oil.

Illustrative of an application of the present invention is an automotive shop break-in oil having a viscosity of 165 seconds, Saybolt Universal at 100 F. Under conditions of use, the oil becomes mixed with cooling water which must be removed before the oil can be reused. Ordinarily, the oil-water mixture is pumped to a settling basin where it remains under quiescent conditions for a long period of time to allow the water to settle out by gravity. After settling the oil is then reused.

As an example of the base oils which may be used in the present invention are hydrocarbon oils, e.g., petroleum oils having a viscosity of about 75 to 400 seconds, Saybolt Universal at 100 F. The choice of the particular base oil selected will be determined by the use intended for the lubricant. The oil may be a petroleum distillate or residium oil or mixtures thereof, or may be a synthetic hydrocarbon oil falling within the above described viscosity range. Also, the oil may be treated in various ways, such as by acid treating, but preferably, is a solvent refined oil. The base oil may contain, in addition, other additives such as pour point depressants, anti-foam agents,

2 antioxidants, viscosity index improvers or other such additives which do not act to destroy the improved demulsibility characteristics of the petroleum oil composition.

The zinc dialkyl dithiophosphate may be prepared by reacting an alcohol or a mixture of alcohols containing from about 3 to 16 carbon atoms per molecule with phosphorus pentasulfide and treating the reaction product with a zinc salt, such as zinc oxide. The alcohol employed for this purpose may be octyl or decyl alcohol, but preferably a mixture of isopropyl and decyl alcohols is used in the' preparation. The preparation of this compound is further described in the publication Organophosphorus Compounds" by G. M. Kosolapoif, published by John Wiley & Sons (1958). The zinc dialkyl dithiophosphate may be obtained commercially, dissolved in a light base oil and prepared for immediate use in compounding a lubricant composition. From about 0.1% to 5% of the zinc dialkyl dithiophosphate may be added to the base oil, and preferably from about 0.5% to 2%.

- Alkali metal salts of sulfonated castor oil may be prepared by sulfonating castor oil and neutralizing the sulfonated oil with an alkaline salt of an alkali metal such as lithium, sodium, etc. While the various alkali metal salts of sulonated castor oil may be employed in the inven tion, it is preferred to use a sodium salt of sulfonated castor oil. A commercially available sodium salt of sulfonated castor oil is Surpasol CN-75, marketed by Hart & Harrington, Inc. metal salt of sulfonated castor oil employed in the invention may vary over a wide range such as from about 1 to 10% by weight, and preferably about 2 to 5%, of the zinc dialkyl dithiophosphate added to the base oil.

The following examples illustrate lubricant compositions provided by the present invention. These examples are given solely by Way of illustration and are not intended to limit the scope of the invention.

EXAMPLE I Condensation product of a chlorinated paraflin wax with naphthalene in the presence of an aluminum chloride catalyst (pour point depressant) 2.0% (Wt). Dimethyl silicone anti-foam agent 1 p.p.m. Sodium salt of sulfonated castor oil 0.05% (Wt). S.A.E. 10 petroleum oil Remainder.

A series of lubricant compositions were prepared as shown in Table I, including the lubricant compositions of the invention and also compositions employing other demulsifying agents. These compositions were then tested to determine their demulsibility characteristics.

The test method employed was as follows: place 225 ml. of test oil and 25 m1. of water in a 250 m1. glass-stoppered graduated cylinder fitted with a bottom draw-0E cock; invert the cylinder 10 times; allow the cylinder to stand quiescent for 15 minutes at room temperature; measure the volume of clear separated water; add fresh water equal to the amount drawn oil and re-test. This test procedure is repeated 10 times. At least of the Water must separate after each 15 minute settling period in order for the lubricant to be satisfactory.

The amounts of the alkali- Table 1 Water Separa- Test tion N 0. Composition Remarks ml. Percent 1 Base 011 1 9 36 Foiled first test. Base Oil 1 plus- 2..-.-. 1.2% Zinc isopropyl decyl 10 40 Do.

dithiophosphate. 3 0.1% "Surpasol (IN-753"... 0 Do. 4 1.25% Surpasol CN75 18. 4 73. 6 Failed before tests completed. 5 1.2% Zinc lsopropyl-deeyl 12 48 Failed first dithiophosphate test. 0.10% dilauryldimethyl ammonium bromide.

6 1.2% Zine isopropyl-deeyl 14 56 D0.

dithiophosphate 0.05% Mahogany Soap.

7 1.2% Zinc lsoprorlulyl-decyl 17 08 D0.

dithiophosp ate 0.05% ethylene oxide condensation product of sorbitan mono-olente.

8 1.2% Zinc isoproplyl-deeyl 24. 8 99. 2 Pass dithiophosp ate 0.5025% Surpesol ON- 7 9 1.2% Zinc isopropyl-decyl 24. 6 98. 4 Do.

dithiophosphate 05057,, "Surpasol ON- 4 1 Base Oil-2.0% Condensation product of a chlorinated paratfin wax with naphthalene in the presence of an aluminum chloride catalyst (Pour Point Depressant) 1 ppm. Dlmethyl silicone anti-foam agent. RemainderS.A.E. 10 petroleum oil.

The above data demonstrates the desirable demulsibility characteristics of the lubricant compositions of the present invention and indicates that these properties are not significantly depleted with continued use.

Percentages given herein and in the appended claims are weight percentages unless otherwise specified.

Having described our invention, what we claim is:

1. A lubricant composition resistant to the formation of stable emulsions with water comprising a major proportion of a hydrocarbon base oil, about 0.1% to 5% of a zinc dialkyl dithiophosphate wherein the alkyl groups contain from about 3 to 16 carbon atoms, and about 1% to 10% of an alkali metal salt of sulfonated castor oil based upon the total amount of said zinc dialkyl dithiophosphate.

2. A lubricant composition resistant to the formation of stable emulsions with water comprising a major proportion of a hydrocarbon base oil, about 1.2% of a zinc isopropyl-decyl dithiophosphate wherein the alkyl groups contain from about 3 to 16 carbon atoms, and about 0.025% to 0.05% of an alkali metal salt of sulfonated castor oil.

3. A lubricant composition resistant to the formation of stable emulsions with Water comprising a major proportion of a petroleum base oil having a viscosity of about 165 seconds, Saybolt Universal at 100 F., about 1.2% isopropyl-decyl dithiophosphate and about 0.025% to 0.05 of a sodium salt of sulfonated castor oil.

4. The lubricating composition of claim 1 wherein said hydrocarbon base oil has a viscosity of about to 400 seconds, Saybolt Universal at F.

5. The lubricating composition of claim 1 wherein said zinc dialkyl dithiophosphate is present in an amount between about 0.5% to 2%.

6. The lubricating composition of claim 1 wherein said alkali metal salt is present in an amount between about 2% to 5% of said zinc dialkyl dithiophosphate.

7. The lubricating composition of claim 1 wherein said alkyl groups are an isopropyl group and a decyl group.

8. The lubricating composition of claim 1 wherein said salt is a sodium salt of sulfonated castor oil.

References Cited in the file of this patent UNITED STATES PATENTS 2,369,632 Cook et al. Feb. 13, 1945 2,689,220 Mulvany Sept. 14, 1954 2,798,045 Buck et a1. July 2, 1957 2,852,465 Jensen Sept. 16, 1958 3,001,940 Watson et al Sept. 26, 1961 3,004,916 Ertelt Oct. 17, 1961 

1. A LUBRICANT COMPOSITION RESISTANT TO THE FORMATION OF STABLE EMULSIONS WITH WATER COMPRISING A MAJOR PROPORTION OF A HYDROCARBON BASE OIL, ABOUR 0.1% TO 5% OF A ZINC DIALKYL DITHIOPHOSPHATE WHEREIN THE ALKYL GROUPS CONTAIN FROM ABOUT 3 TO 16 CARBON ATOMS, AND ABOUT 1% TO 10% OF AN ALKALI METAL SALT OF SULFONATED CASTOR OIL BASED UPON THE TOTAL AMOUNT OF SAID ZINC DIALKYL DITHIOPHOSPHATE. 